Abrasive-treating apparatus

ABSTRACT

A treating apparatus includes particle feed means which supplied treating particles, such as abrasive shot, to a nozzle under pressure. Metering means is disposed between the feed means and nozzle and is actuated by the pressure to open and close communication therebetween. The metering means includes a particle outlet extending from the feed means and having a defined geometric shape with a metering gate being in sliding contact with the outlet. The metering gate also has an opening of a defined geometric shape so that the degree of registry of the openings controls the amount of particle flow to the nozzle.

United States Patent Appl. No. Filed Patented Assignee ABRASIVE-TREATING APPARATUS 9 Claims, 5 Drawing Figs.

Int. Cl

Field of Search References Cited UNITED STATES PATENTS 12/1894 Mathewson 5/1926 Jorgensen 1.

3,521,407 7/1970 Nalley et al 51/12 FORElGN PATENTS 386,031 1/1933 Great Britain 51/12 Primary Examiner- Lester M. Swingle Att0rneys David E. Dougherty and Robert E. Walter ABSTRACT: A treating apparatus includes particle feed means which supplied treating particles, such as abrasive shot, to a nozzle under pressure. Metering means is disposed between the feed means and nozzle and is actuated by the pressure to open and close communication therebetween. The metering means includes a particle outlet extending from the feed means and having a defined geometric shape with a metering gate being in sliding contact with the outlet The metering gate also has an opening of a defined geometric shape so that the degree of registry of the openings controls the amount of particle flow to the nozzle.

FATENTED [15628 :97:

ABRASIVE-TREATING APPARATUS BACKGROUND OF INVENTION Various pressure tank treating apparatus are in existence. One such apparatus is a pressure tank abrasive blasting machine which is described in commonly assigned copending application Ser. No. 645,812, filed June 13, 1967, now U.S. Pat. No. 3,521,407, filed July 21, 1970. This treating apparatus includes a plurality of pressurized chambers for supplying treating particles to a nozzle which is also under pressure. The lowermost chamber communicates with the nozzle by some type of valve or metering gate to regulate the flow of particles to the nozzle. Generally, these conventional metering devices include an opening in the feed chamber which is selectively closed by the reciprocating movement of a plunger having, for example, a ball valve attached at its end for seating against the feed chamber opening. Although this type of metering arrangement works for many operations it cannot meter to very small abrasive flows as will be explained hereinafter.

There is, therefore, a need for an effective metering device which can be incorporated in treating apparatus particularly on pressure tank abrasive blasting machines.

SUMMARY OF INVENTION An object of this invention is to provide a metering arrangement which can be incorporated in treating apparatus, particularly pressure tank abrasive blasting machines.

A further object of this invention is to provide such a metering arrangement which gives a very small abrasive fiow as well as a high flow and which can be easily and accurately adjusted to give fine increments of variable fiow.

A further object of this invention is to provide such a metering arrangement which is fail safe in operation.

A still further object of this invention is to provide such a metering arrangement which can be incorporated in the type of treating apparatus shown in commonly assigned copending application Ser. No. 645,812, filed June 13, 1967, now US Pat. No. 3,521,407, dated July 21, 1970.

In accordance with this invention the treating apparatus includes particle feed means for storing and supplying the treating particles. A treating nozzle communicates with the feed means, and both the feed means and nozzle are pressurized. Metering means between the nozzle and feed means is actuated by the pressure means to selectively permit the flow of particles to the nozzle. The metering means include a particle outlet extending from the feed means and having an opening of defined geometric shape. A metering gate is disposed in sliding contact with the outlet and also has an opening of defined geometric shape so that the degree of registry of the openings determines the amount of particle flow to the nozzle.

Adjusting means may be utilized for limiting the maximum amount of particle fiow. Closing means may be provided in a metering chamber to urge the metering gate toward a closed position, while opening means such as a diaphragm may be connected to the metering gate and be responsive to the pressure in the nozzle so as to overcome the closing action of the closing means.

THE DRAWINGS FIG. I is a cross-sectional plan view of a prior art metering arrangement;

FIG. 2 is a plan view of a metering arrangement in accordance with this invention;

FIG, 3 is an elevation view in section of the metering arrangement shown in FIG, 2; and

FIGS. 4 and 5 are plan views ofa portion of the metering arrangement shown in FIGS. 2-3 showing alternate constructions.

DETAILED DESCRIPTION FIG. I shows a conventional prior art metering arrangement 2 which includes a feed chamber having for example a valve seat 4 which is opened and closed by the reciprocating movement of a ball valve 6 being mounted on the end of a plunger. When the plunger is moved away from seat 4 a 360 opening is obtained as illustrated in FIG. I. In order to obtain flow through the opening the minimum opening must be greater than the largest diameter of shot or particle 8 being used. Once the plunger is opened to this opening the particles can flow around the greater part of the 360 opening. The flow area is then approximately the circumference of the inner surface of the valve seat 4 times the opening width required to flow the largest piece of abrasive shot. For example with a one inch diameter hole in the seat 4 and a l/lo-inch-diameter abrasive particle, the total opening would be approximately 3.14 times 1 times 0.062 or 0.19 square inch. This approximation method is used to illustrate in a simple manner the resulting area. The actual area would of course be the difference between the two areas obtained from the dimensions of the valve seat 4 and ball valve 6. Such conventional arrangements also include adjusting screws secured to the end of the plunger. However, with these arrangements a small manipulation or adjustment of the screw results in a large area increase which makes fine adjustments for variable flow both difficult and inaccurate.

FIGS. 2-3 illustrate a metering arrangement in accordance with this invention. As indicated most clearly in FIG. 3 the metering arrangement is utilized with a treating apparatus 10. Apparatus 10 is preferably of the type described in detail in commonly assigned copending application Ser. No. 645,812, filed June 13, 1967, now US. Pat. No. 3,521,407, dated July 21, 1970. Since the details are referred to in this copending application the repetition of such details is not necessary herein except where desired for a clearer understanding of this invention.

Apparatus 10 includes a plurality of chambers the lowermost of which is the feed chamber 12 illustrated in FIG. 3. The treating apparatus also includes a treating nozzle 14. Both feed chamber 12 and nozzle 14 are pressurized during a treating operation. A metering arrangement 16 is disposed between the feed chamber 12 and nozzle 14 for selectively feeding particles to the nozzle. As shown in FIG. 3 arrangement [6 includes a gate spout or outlet 18. Outlet 18 has an opening of defined geometric shape such as the square or rectangular opening 20 illustrated in FIGS. 2 and 4. Directly under opening 20 and in sliding contact with outlet 18 is sliding gate 22 which likewise has an opening 24 of defined geometric shape. Sliding gate 22 is reciprocated in the direction indicated by the arrow 26 and is actuated to close flow through the outlet 18 by spring 28 which may be any suitable spring such as a compression spring. Conversely sliding gate 22 is actuated to open flow by air pressure acting against diaphragm 30. In order to obtain fine infinitely variable control a screw or threaded rod 32 is also provided to limit or control the maximum opening movement of sliding gate 22. Screw 32 can also be manipulated by turning exposed handle 33 to tune the effective opening obtained by registry of openings 20 and 24 while the actual blasting operation takes place to give thereby optimum flow through the nozzle 14. 14.

When the air pressure to the feed chamber 12 and nozzle 14 is turned on, the pressure in the metering chamber 34 acts on diaphragm 30 to move the diaphragm from the position indicated in phantom to the position indicated in solid so that communication is then obtained between feed chamber 12 and nozzle 14. In this respect since nozzle 14 communicates with chamber 34 the air flowing through nozzle 14 also flows into chamber 34 to cause gate 22 to open at the beginning of operation. The movement of diaphragm 30 results in sliding gate 22 moving until it is stopped at a predetermined point by contact of adjusting screw 32. The abrasive flows through the orifice resulting from registry of openings 20 and 24 to nozzle section 36 where it is picked up by air and carried through nozzle 14.

When the pressure is turned off at the end of the blast cycle spring 28 automatically closes sliding gate 22. With the metering arrangement 16, as an added safeguard, if air is lost through malfunction sliding gate 22 will again automatically close. Thus the metering arrangement is fail safe.

To assure that there are no abrasive leaks when nozzle 14 is in a closed position spring 38 is provided. As shown in FIGS. 2 and 3 the leaf spring 38 is U-shaped with its legs 40 straddling the opening 24 in the sliding gate 22. Spring 38 thereby acts as a guide means to apply pressure against the lower side of sliding gate 22 and thus assures sliding contact with outlet 18. Edge 42 of outlet 18 is kept relatively sharp to prevent abrasive from wedging between the edge and sliding gate. Maximum wear life of sliding gate 22 and better sealing results by using a polyurethane or similar material.

The provision of diaphragm 30 to completely seal the remote portion of metering chamber 34 is also beneficial in that the diaphragm 30 prevents abrasive particles and dust from reaching the components such as spring 28 and threaded rod 32. This sealed off portion includes vent 31 which is exposed to the atmosphere.

The geometric shape of openings 20 and 24 may take different forms. For example, as shown in FIG. 4 each opening is of square or rectangular shape. FIG. 5, however, shows openings 20a and 24a to be rounded or of circular form. An important characteristic, however, of the hole arrangements is that at least one of the holes has a narrow or pointed lead surface 44 which makes initial registry with the other hole when the pair of holes first become superimposed. In this manner the resultant opening becomes progressively larger in very fine increments by manipulation of exposed handle 33 at the end of rod 32. With this type of hole arrangements, fine abrasive flow control can be obtained. For example MG. 4 shows the minimum opening which will permit three grains of abrasive particles to be side by side. lf the abrasive particles have a l/l6-inch diameter, an opening with an area of 0.0169 square inchcould be used for minimum flow. This is in sharp contrast to conventional arrangements which would require an opening of 0.19 square inch (such as discussed with respect to FIG. 1) or over l times greater than with the arrangement of FIG. 4. Test results have shown for example that the inventive gate is capable of continuously flowing a minimum 5.6 pounds per minute of l/l6-inch-diameter shot and as low as l/l0 pound per minute of shot having 0.007 inch diameter. The accuracy of flow repeatedly was found to be within percent.

With the metering arrangement 16 a given increase in opening along the direction of axis 26 actually results in a smaller increase in orifice. For example if the prior art FIG. I arrangement would have an initial opening of 1/16 inch the area would be 0.19 square inch. If the opening in FIG. I is then increased 1/16 inch, the area becomes approximately 0.38 square inch which is a 100 percent increase. With the inventive arrangement such as illustrated in FIG. 4 if the area is originally 0.19 square inches and the opening is then increased l/l6 inch the resulting area will only be 0.23 l -square inch for an area increase of only 23 percent in contrast to the I00 percent area increase of conventional arrangements. This comparison strikingly illustrates how the inventive arrangement permits accurate, fine flow adjustments.

What is claimed is:

I. A treating apparatus comprising particle feed means for storing and supplying treating particles, a treating nozzle communicating with said feed means, pressure means for pressurizing said feed means and said nozzle, metering means causing the selective communication of said nozzle with said feed means. said pressure means actuating the opening and closing of said metering means, said metering means including a particle outlet extending from said feed means, said outlet having an opening ofdefined geometric shape, a metering gate disposed in sliding contact with said outlet, said metering gate having an opening of a defined geometric shape whereby the degree of registry of said openings in said outlet and said gate controls the amount of particle flow from said feed means to said nozzle, one of said defined geometric shapes including a narrow leading surface with its opening becoming wider in a direction away from said leading surface, and said openings being disposed in the path of motion of each other in such a manner that at the beginning of registry of said openings said leading surface of one opening makes first registry with the other opening.

2. An apparatus as set forth in claim 1 including adjusting means connected to said gate for limiting the maximum amount of particles flowing through its opening.

3. An apparatus as set forth in claim 2 including a metering chamber communicating with said nozzle, said metering means being in said metering chamber, closing means acting upon said metering gate to urge said metering gate toward a closed position, and opening means responsive to the pressure in said nozzle acting upon said metering gate to urge said metering gate toward an open position whereby sufficient pressure in said nozzle causes said gate to open.

4. An apparatus as set forth in claim 3 wherein said opening means includes a diaphragm connected to said metering gate.

5. An apparatus as set forth in claim 4 wherein said adjusting means includes an adjustable stop member in said chamber disposed in the path of motion of said metering gate when said metering gate is moving in its opening direction.

6. An apparatus as set forth in claim 5 including guide means in said chamber for maintaining said gate in contact with said outlet.

7. An apparatus as set forth in claim 6 wherein said diaphragm seals off a portion of said metering chamber, said closing means being a spring housed in said sealed-off portion, said stop member being a threaded rod extending into said sealed-off portion and having an exposed handle, and a vent in said sealed-off portion.

8. An apparatus as set forth in claim 7 wherein said openings are of the same defined geometric shape.

9. An apparatus as set forth in claim 8 wherein said guide means is a U-shaped spring with its legs disposed for straddling the opening of said gate, and said metering chamber tapering downwardly toward said nozzle. 

1. A treating apparatus comprising particle feed means for storing and supplying treating particles, a treating nozzle communicating with said feed means, pressure means for pressurizing said feed means and said nozzle, metering means causing the selective communication of said nozzle with said feed means, said pressure means actuating the opening and closing of said metering means, said metering means including a particle outlet extending from said feed means, said outlet having an opening of defined geometric shape, a metering gate disposed in sliding contact with said outlet, said metering gate having an opening of a defined geometric shape whereby the degree of registry of said openings in said outlet and said gate controls the amount of particle flow from said feed means to said nozzle, one of said defined geometric shapes including a narrow leading surface with its opening becoming wider in a direction away from said leading surface, and said openings being disposed in the path of motion of each other in such a manner that at the beginning of registry of said openings said leading surface of one opening makes first registry with the other opening.
 2. An apparatus as set forth in claim 1 including adjusting means connected to said gate for limiting the maximum amount of particles flowing through its opening.
 3. An apparatus as set forth in claim 2 including a metering chamber communicating with said nozzle, said metering means being in said metering chamber, closing means acting upon said metering gate to urge said metering gate toward a closed position, and opening means responsive to the pressure in said nozzle acting upon said metering gate to urge said metering gate toward an open position whereby sufficient pressure in said nozzle causes said gate to open.
 4. An apparatus as set forth in claim 3 wherein said opening means includes a diaphragm connected to said metering gate.
 5. An apparatus as set forth in claim 4 wherein said adjusting means includes an adjustable stop member in said chamber disposed in the path of motion of said metering gate when said metering gate is moving in its opening direction.
 6. An apparatus as set forth in claim 5 including guide means in said chamber for maintaining said gate in contact with said outlet.
 7. An apparatus as set forth in claim 6 wherein said diaphragm seals off a portion of said metering chamber, said closing means being a spring housed in said sealed-off portion, said stop member being a threaded rod extending into said sealed-off portion and having an exposed handle, and a vent in said sealed-off portion.
 8. An apparatus as set forth in claim 7 wherein said openings are of the same defined geometric shape.
 9. An apparatus as set forth in claim 8 wherein said guide means is a U-shaped spring with its legs disposed for straddling the opening of said gate, and said metering chamber tapering downwardly toward said nozzle. 